α-吡喃酮并咔唑基光引发剂的合成及性能研究

The conjugation of coumarin and carbazole skeleton (coumarin and carbazole share a benzene ring) can obtain pyrano[3,2-c]carbazol-2(7H)-one and its isomers with excellent optical properties. Therefore, we apply for this project from the aspect of molecular design, and the aim is to achieve a series of single- and two-photon sensitive photoinitiators with desired optical properties based on these π-conjugated systems. . The research contents of this project can be divided into several aspects, the first is the synthesis of 4-methyl pyrano[3,2-c]carbazol-2(7H)-one and its isomers (coumarin and carbazole share a benzene ring), and then is the modification of these π-conjugated cores with different type of photoliable groups to prepare a variety of photoinitiators, such as photoradical generators, photoacid generators and photobase generators and so on; On the basis of successful organic synthesis, the following research will combine theoretical calculation and various characterization technologies to analyze the photochemical and photophysical properties of these photoinitiators, and to elucidate the structure-activity relationship between various optical properties of photoinitiators and the fine functionalization of π-conjugated core structures.. This project is characterized firstly by a suitable middle size π-conjugated systems which guaranteed the maximum absorption peaks should be localized in the range of 365nm to 425nm, and the absorption spectra of the designed photoinitiators can match with emission spectra of the increasingly popular LED light sources. At the same time, the large π-conjugated systems are usually accompanied by large two-photon absorption cross-sections. In last, besides the free radical polymerization, cationic polymerization and thiol-epoxide polymerization systems initiated by photoacid and photobase generators have the advantage of low shrinkage. . The advantage of this project is to provide a quite new molecular research platform, especially different kinds of photoinitiators can be integrated on the same conjugated skeletons. The special conjugated system of isomers can explain the mechanism of various optical properties of different types of photoinitiators from molecular level. Besides, the optimized photoinitiators have a lot of potential applications in the fields of photocuring, 3D printing, two-photon microfabrication, microelectronics and so on.

香豆素和咔唑骨架共轭结合会得到光学性质优良α-吡喃酮并咔唑光吸收基团。本项目的研究目标就是以此π-共轭基团为核心光吸收基团，通过分子结构设计得到单、双光子敏感的光引发剂。主要研究内容是设计多种同分异构体的α-吡喃酮并咔唑，并通过引入不同类型的光可裂解基团，合成出光生自由基、光生酸、光生碱等系列光引发剂，然后结合理论计算和各类表征技术，阐明光解机理，分析光学性能和共轭结构细微改变之间的构效关系。α-吡喃酮并咔唑类共轭结构具有平面构型，赋予分子较大的双光子吸收截面的同时其衍生的各类光引发剂的吸收光谱可匹配日益普及的LED光源的发射光谱。另外，光生酸剂和光生碱剂引发的阳离子聚合和硫醇-环氧等非自由基聚合体系可满足较低的收缩率的要求。本项目提供了一种新的光引发剂分子研究平台，同分异构的共轭体系可以从分子级水平解释不同类型光引发剂光性能的机理，优选的结构在光固化、双光子构筑等领域都有广泛的应用前景。

光引发剂是一类在外界光、电子束等辐射下能够分解产生特殊活性种，例如自由基或者强酸的一类化合物。由于其光化学反应过程时空可控的优势，被广泛地应用于光固化、光刻胶和计算机直接制版（CTP）等体系中，在涂料、微电子胶粘剂、印刷、光刻等领域有着重大的实际应用。因此，项目的研究即从开发出系列的高性能的光引发剂分子，包括自由基引发剂和光生酸剂展开。. 本项目的主要研究内容就是致力于设计并制备出一系列带有较大共轭体系的光引发剂分子，这类分子可以带有不同类型的光可裂解基团，从而在近紫外、可见和近红外 (双光子模式)等光子激发下可以有效地分解并产生各种活性种。方案是通过系统的分子工程，把不同的活性基团引入到以香豆素并咔唑、吡唑啉等吸光基团结构中，利用理论计算方法证实这些分子结构的光分解机理，使光吸收和光敏感材料在同一分子体系中实现协同，研究分子结构与其性能之间的内在关系，实现光引发剂性能的不断优化。. 研究的重要结果在于研究了不同共轭体系的光引发剂的合成及其性能，并通过光固化等具体应用探索了其应用潜力，特别是在近紫外-可见光LED激发下和800nm激光激发下的单光子和双光子引发聚合的能力。研究发现，大π-共轭型结构赋予其吸收红移至近紫外-可见光区的优势，波谱变宽，摩尔消光系数增大等特点，这些都增强了其实用性。优化的分子结构的光分解量子产率达到了0.3~0.6这个范围，双光子吸收截面δ~100GM，这些关键数据都对其应用有巨大的促进作用。. 本项目的科学意义在于制备的几个系列的光引发剂分子，不仅丰富了这一类高性能的光学分子的数量，而且通过在机理方面的研究也为后来的研究工作提供了坚实的基础。特别在光固化和微电子领域具有非常大的应用潜力，同时，这类分子结构可以有效提高在近红外区域的双光子吸收截面，使其可应用于双光子激发相关领域。制备出的光生酸剂能够在i线光刻、紫激光计算机直接制版、以及聚合物三维微细加工等领域中有很高的应用价值。